The Gunners conceded in the 76th minute when Jon Walters’ flick struck Laurent Koscielny’s arm in the box and referee Mike Jones awarded a penalty, which the Potters forward stepped up and converted.

Wenger described the goal as a “nice gift” for Stoke from Jones, but was also in no doubt that Arsenal had not been good enough in attack during the contest.

And with the result, plus leaders Chelsea’s 3-1 win at Fulham, meaning Arsenal are now four points adrift of the Blues with each having 10 top-flight games to go, Wenger said: “It is not slightly worrying - it is a big worry for us to lose a game like that. It is a massive setback.

“It was a good defensive performance and, overall, we were unlucky to lose this game. But offensively we didn’t create enough. Our offensive game was poor, considering our standards. And, at the end of the day, we didn’t score because of that.

“We conceded a goal which was a nice gift from the referee, but that can happen.

“He is one yard away - how can he take his hand away? He has no time to take his hand away from the ball.

“He had no intention at all, but we cannot influence the decision of the referee and I feel going forward we were not good enough to create chances, and that is why we were punished.”

Wenger insisted his team are “not fragile at all”, and, on the prospect of them bouncing back, he said: “I’m not worried.

“But we didn’t produce the performance we wanted and to win a title, when you are expected to perform, you have to perform. It is as simple as that.”

Arsenal striker Olivier Giroud in particular was on the end of some rough-looking treatment during the game, with Stoke midfielders Glenn Whelan and Charlie Adam appearing to stand on the France international.

Wenger after the match made reference to the Potters’ physicality, but was reluctant to speak about individual incidents.

He said: “You have to give credit to Stoke. They defended well, with resilience, and made the game very physical.

“We knew that would be the case before the game, though. They have the highest number of fouls in the Premier League. But we didn’t cope well enough with it and at the end of the day we were punished.”

Asked about the challenges on Giroud, Wenger added: “I don’t want to talk about the referee. I have nothing to say about that.

“I am long enough in the game to make my own judgement and I prefer to concentrate on our own performance.”

Belsize Park scored seven tries to produce their sixth successive victory since the turn of the year, beating Hitchin 51-15, but there was no change in the London North-West Division Three promotion race with four games to go.

Hampstead coach Peter Breen hailed Saturday’s 17-7 home win over Staines as one of the best displays of the season as the hosts completed the double over their visitors in London North-West Division Two.